Superheater



Patented Oct 18, 1932 UNITED STATES;

PATENT OFFICE cHAnLEs w. eonnomor 'MUNSTER, INDIANA, ASSIGNOR TO THESUPERHEATER COMPANY, 012* NEW YORK, N. Y.

SUPERHEATER Application filed November 17, 1931. Serial No. 575,498. I

vantages gained by using the feature ofrad ant heat absorption.

V It is an object of my invention to provide a design whereby the abovementioned difficulty may be overcome.

. In accordance W1 h my lnvention, asuperheater having radiant typeelements is combined with the water wall of a furnace chamber so thatboth theportion of the elements receiving the most intense radiation andthe I portion of the elements carrying the highest temperature steam areprotected from overheating by counter-radiation to. an element of thewater wall while theportion of the elements carrying the highesttemperature steam is also somewhat screened from radiation by the waterwall.

The novel features of the invention will be pointed out in the appendedclaims. The invention itself, however, and its-objects and advantageswill best be understood from a detailed description .of an arrangementin accordance with the invention and such a description will now begiven, in connection with the accompanying drawing, of a reheatersuperheater installationgselected by way of example from a'number ofpossible embodiments of theinvention. In the drawing: Fig. 1 is ahorizontal sectional view through a portion of a'boiler furnace having acombined water wall and I radiant type superheater installed along oneside thereof. Fig. 2 is a vertical section on the line 22 of Fig. 1.Fig. 3 is an elevation of a portion of an arrangement illustrated inFig. 1.

Fig. 4 is a detailed sectional view on the line 44 of Fig. 2.

The elements of a radiant type superheater or reheater are subjecttosevere conditions at times when the steam fiow is reduced after a periodof full load, since the radiant heat does not drop off nearlyas'rapidlyas the 8 load. The consequence has been that, if the superheater isdesign-ed to furnish steam at the temperature whichthe steel is capableof standing at full load, the metal will be damaged when the load fallsoff, but if the superheater is designed so that the maximum temperaturesattained do not damage the metal of its tubes, the steam temperature atfull load is not as high as desirable for rea sons of efliciency.

their inlets to ensure a high steam tempera-v ture at their outlets,their portions nearer their inlets being protected from overheating tosome extent by radiation to' a cooler surthe outlet sections of theelements'are close enough to such cooler objectto be. protected somewhatby radiation thereto;

The installationillustrated in the drawing comprises a furnace chamber10 having a wall 12. Parallel to the wall 12, I arrange a row of Waterwall tubes 14, 14, each substantially vertical and parallel to wall 12,and connected at its lower end to inlet header 16 and at its outer endtoan outlet header 18. In'the average case,the headers 16 and 18 areconnected into the thermo-syphonic circulation of the boiler. Associatedwith certain of the tubes 14, I have shown superheater elements 20, 20in accordance with my present invention. The elements 20 have inletportions 208? connected to a header 22 for saturated steam and outletportions 206 con- V Inaccordance with my invention, the'su- 1 perheaterelements are exposed sufficiently to direct radiation in their portionscloser to Y able apertures in the lower portion of such fromoverheatingby the fact that they receive relatively cool steam and, further, by thefact that they are close enough to the front faces of the water tubes 14to discharge heat to such tubes byradiation. It will be seen furtherthat the inlet portions 20a of elements 20 are arranged in pairs one oneach side of the perpendicular to wall 12 through the centre of one oftubes 14. This forms a symmetrical arrangement whereby the elements 20receive substantially equal amounts of radiant heat, but I do not limitmyself to this. At their upper ends, inlet portions 20a are connected tothe outgoing portions 20?) by return bends 26, 26. Headers 22 and 24 maytherefore be conveniently placed at the same level outside wall 12, asshown. The outlet portions 20?) of elements 20 receive steam at aconsiderable temperature and, to

prevent them from overheating, when the flow of steam -is less than thatat full load, the portions 206 are run close to the wall 12 whereby theyreceive less radiation due to their greater distance from the combustionzone of the furnace and they are further protected by placing them wherethey are at least partly shielded from radiation by tubes 14. As appearsclearly in Fig. 1, the outlet portions 20?) of some element 20 are notdirectly behind their associated water wall tubes 14, but they,nevertheless, are shielded thereby from the radiation from aconsiderable sector of the combustion zone. The entire lengths ofportions 206, however, need not be screened from the full radiation ofthe furnace and, as best appears in Fig. 3, I have shown relativelyshort sections 20 on the outlet sides ofthe return bends 26 which areexposed to the furnace radiation without any protecting screeningwhatever. At point 21, however, not far below the bends 26, eachdischarge section or portion of the elements bends rearwardly towardwall 12 and, in most instances, toward the perpendicular to wall 12 thruthe centre of one of the water tubes 14. By so bending the tube to therear of the planeof tubes 14, the radiation received by portions 20?; isdecreased both on account of the additional distance from the furnaceand on account of the partial screening of one of the tubes 14. When theportion 20b bends also toward the perpendicular to the tube thescreening effect is, of course, increased. Portions 20?) are furtherprotected from overheating by radiation to tubes 14. It will be seenthat two elements 20 preferably are associated with one water wall tube14. However, I do not limit myself to this.

As shown more particularly in Fig. 1, the

elements 20, in the particular installation il- I lustrated, form only aportion of the total header 24 whenever the flow of temperature of thesteam from elements 20 is greater than that needed for the prime moveror other steam using device supplied by the installation.

A convenient arrangement of elements 20 and 30 is one illustrated inFig. 2 and in which the elements 20 are connected into the lower facesof headers 22 and 24 while elements 30 are connected into the upperfaces of such headers. It will be apparent further from Fig. 1 that theelements 30 as well as the portions 20?) of elements 20 receivesubstantial amounts of heat by con: vection as well as by radiation.

What I claim is: V

1. The combination with a water wall tube of a furnace of a superheaterelement having a pipe length in the furnace close to the furnace side ofsaid tube and connected'to receive saturated steam, and a lengthconnected to receive steam directly from said first length and todischarge steam from the element, said second length having its greaterportion farther from the furnace than said wall tube and screened fromradiation thereby to some extent, but arranged to receive heat byconvection.

2. The combination of a furnace provided with a water wall having spacedsubstantially vertical tubes, and a superheater having elements arrangedto receive radiant heat from the furnace and some of which are far therfrom the furnace than said tubes thru their entire extent and others ofwhich have inlet portions extending into the furnace farther than saidwater wall tubes and lying closely adjacent to the furnace face thereofand have outlet portions farther from the furnace than said water walltubes throughout their greater portions and partially screened fromradiation thereby.

3. The combination as set forth in claim 2 and in which the superheaterelements are all approximately twice the length of the water wall tubes.7

4. The combination as set forth in claim 2 and in which the outletportions of the elements are further protected from overheatingby'be'ing arranged to radiate to some extent to the water wall tubes.

5. The combination as set forth in claim 2 together with inlet andoutlet headers at substantially the same level and connected to theinlet and outlet portions of the elements.

6. The combination with water wall tubes of a furnace, of a pair ofsuperheater elements associated with each of said tubes and each havinga pipe length in the furnace close to the furnace side of its associatedtube, said lengths lying one on each side of the perpendicular to thefurnace wall thru the water tube and connected to receive saturatedsteam, said elements having also each .a length connected to receivesteam directly from said first length and to discharge steam from theelement, said second length having its greater portion farther from thefurnace than said wall tubes andscreened from radiation thereby to someextent as well as being further protected from overheating by beingarranged to radiate heat to some extent to one of said wall tubes.

7. The combination as set forth in claim 6 together with a group ofelements having both their inlet and outlet portions farther from thefurnace than the water wall tube,

and common inlet and outlet headers for both groups of elements.

In testimony whereof I aflix my signature.

CHARLES W. GORDON.

